1. Technical Field
This invention relates to the field of speech recognition software, and more particularly, to speech recognition software as implemented on handheld or other mobile devices.
2. Description of the Related Art
Speech recognition is the process by which an acoustic signal received by microphone is converted to a set of text words, numbers, or symbols by a computer. These recognized words may then be used in a variety of computer software applications for purposes such as document preparation, data entry, and command and control. Improvements to speech recognition systems provide an important way to enhance user productivity.
Mobile computing and communications devices, such as personal digital assistants (PDAs) and cellular telephones, have become common tools for performing data management functions, as well as for communicating among multiple users. The portability of such devices and the ability to exchange data among users provides users with added benefits further enhancing user productivity. Additionally, mobile devices can provide users with access to information and services available from computer communications networks.
Notably, the mobile aspect of mobile devices can be a disadvantage regarding data entry. Users are forced to interact with the small visual display of the mobile device. Although such devices can include handwriting recognition applications for data entry, the convenience of a full size keyboard is often lacking. In cases where a keyboard can be attached to a mobile device, the combination of the mobile device and the keyboard, effectively, is no longer mobile. Thus, to use a mobile device while “on the go”, users can be limited to using a stylus as an input device or manipulating physical buttons on the mobile device.
Speech recognition technology can provide an effective method of data entry with regard to mobile devices. For example, a speech recognition system (SRS) can function as a front end user interface to the mobile device or to an application within the mobile device. A SRS can provide the user with several benefits including a hands-free method of data entry. Additionally, a SRS solution for data entry does not immobilize the mobile device by appending unwieldy peripheral devices to it, as is the case with portable keyboards.
Still, SRSs typically require significant system resources to function properly. Accordingly, when SRSs are implemented on mobile computing and communications devices, the limited processing power of such devices can limit the number of speech recognition functions available to a user. For example, after acoustically processing a user spoken utterance, a speech recognition system within a more powerful computer system can compare the proposed result to thousands of possible word models to determine a match. The time required to search the thousands of possible word models can be de minimis. However, such searches can require significantly more time when performed with the limited computing resources of mobile devices. Thus, for efficient operation in a mobile computing environment, a speech recognition application can contain a limited vocabulary or number of recognizable user spoken phrases. For example, if the SRS can typically recognize 10,000 possible word selections, a SRS implementation on a mobile device can limit the possible word selections to only 250. In this manner, the speech recognition application can conserve system resources for increased speed in converting user utterances to text input or system commands. However, this solution can prevent a user from realizing the complete functionality available from a SRS. Specifically, words needed by the user may simply be left out of the SRS vocabulary in an effort to conserve system resources during operation of the SRS. Moreover, with limited selections being available from the SRS, the complete functionality of an application or the mobile device's operating system may not be accessible to the user. Though speech recognition technology can be beneficial to mobile computing and communications device users, still, the aforementioned limitations of using speech recognition technology with such devices have not been fully addressed.